Head-mountable display device and method for displaying an image received from a microscope

ABSTRACT

A head-mountable display device for displaying an image received from a microscope comprises a first display configured to display a first image of a part of an object, the first image received from a microscope. Further, the head-mountable display device comprises a first optical arrangement located in front of the first display. The first optical arrangement comprises at least one lens. Additionally, the head-mountable display device comprises a mounting structure configured to fasten the first display to the head of a user. The head-mountable display device is configured to allow a direct line of sight from a first eye of the user to the object in a field of view of the user outside of the first display while the user is watching the first display through the first optical arrangement, if the mounting structure is fastened to the head of a user. An angle between a display direction and the direct line of sight is less than 50° and the display direction is orthogonal to the first display.

TECHNICAL FIELD

Examples relate to displaying microscope images on head-mountabledisplays and especially to head-mountable display devices and methodsfor displaying an image received from a microscope.

BACKGROUND

Microsurgery often demands a distortion-free magnified stereoscopic viewof the operating field. Digital stereo microscopes can provide suchviews of the operating field. The image can be viewed through eye piecesat the microscope or may be displayed on an external screen or byhead-mountable displays.

SUMMARY

An embodiment relates to a head-mountable display device for displayingan image received from a microscope. The head-mountable display devicecomprises a first display configured to display a first image of a partof an object, the first image received from a microscope. Further, thehead-mountable display device comprises a first optical arrangementlocated in front of the first display. The first optical arrangementcomprises at least one lens. Additionally, the head-mountable displaydevice comprises a mounting structure configured to fasten the firstdisplay to the head of a user. The head-mountable display device isconfigured to allow a direct line of sight from a first eye of the userto the object in a field of view of the user outside of the firstdisplay while the user is watching the first display through the firstoptical arrangement, if the mounting structure is fastened to the headof a user. An angle between a display direction and the direct line ofsight is less than 50° and the display direction is orthogonal to thefirst display.

By allowing the user a direct line of sight to the object while usingthe head-mountable display device, it is easier for the user to interactwith his direct environment (e.g. with other people or tools) incomparison to display devices, which completely or nearly completelyblocking the view of the user.

Another embodiment relates to a head-mountable display device fordisplaying an image received from a microscope. The head-mountabledisplay device comprises a first display configured to display a firstimage of a part of an object, the first image received from amicroscope. Further, the head-mountable display device comprises amounting structure configured to fasten the first display to the head ofa user. The mounting structure comprises a nose piece configured toalign the first display to the first eye of the user. Further, themounting structure is configured to rest less than 40% of the weight ofthe head-mountable display device through the nose piece on the nose ofthe user.

The nose piece may enable a stable alignment of the display to the eyeof the user. In this way, misalignments and movement of the displayrelative to the eye of the user can be significantly reduced or evencompletely avoided. On the other hand, the mounting structure enables asupport of the main portion of the weight of the head-mountable displaydevice on the head of the user but not on the nose. In this way, a highwearing comfort may be enabled.

Another embodiment relates to a head-mountable display device fordisplaying an image received from a microscope. The head-mountabledisplay device comprises a first display configured to display a firstimage of a part of an object, the first image received from amicroscope. Further, the head-mountable display device comprises amounting structure configured to fasten the first display to the head ofa user. Additionally, the head-mountable display device comprises afirst optical arrangement located in front of the first display. Thefirst optical arrangement comprises three lenses. Further, at least onelens of the three lenses is an aspheric lens.

By using at least three lenses between the display and the eye of theuser, a good optical performance with respect to magnification andaberrations may be obtainable. By using at least one aspheric lens, thesize and weight of the optical arrangement may be significantly reducedin comparison to a system using only spherical lenses. Therefore, ahead-mountable display device with small size, low weight and goodoptical performance may be provided.

SHORT DESCRIPTION OF THE FIGURES

Some examples of apparatuses and/or methods will be described in thefollowing by way of example only, and with reference to the accompanyingfigures, in which

FIG. 1 is a schematic illustration of a head-mountable display device;

FIG. 2 is a schematic illustration of another head-mountable displaydevice comprising two displays;

FIG. 3 is a schematic illustration of another head-mountable displaydevice allowing an adjustment of the interpupillary distance;

FIG. 4 a is a schematic illustration of another head-mountable displaydevice in a first state;

FIG. 4 b is a schematic illustration of the head-mountable displaydevice of FIG. 4 a in a second state;

FIG. 5 a is a side view of another head-mountable display device;

FIG. 5 b is a front view of the head-mountable display device of FIG. 5a;

FIG. 5 c is a side view of another head-mountable display device;

FIG. 5 d is a side view of the head-mountable display device of FIG. 5c;

FIG. 5 e is a side view of the head-mountable display device of FIG. 5c;

FIG. 5 f is a side view of another head-mountable display device;

FIG. 5 g is a side view of the head-mountable display device of FIG. 5f;

FIG. 5 h is a side view of the head-mountable display device of FIG. 5f;

FIG. 6 is an illustration of a user view;

FIG. 7 is a schematic illustration of another head-mountable displaydevice and a microscope system;

FIG. 8 is a schematic illustration of a head-mountable display devicewith a nose piece;

FIG. 9 is a schematic illustration of a head-mountable display devicewith an optical arrangement comprising at least three lenses;

FIG. 10 is a schematic illustration of an optical arrangement for ahead-mountable display device; and

FIG. 11 is a flowchart of a method for displaying an image received froma microscope.

DETAILED DESCRIPTION

Various examples will now be described more fully with reference to theaccompanying drawings in which some examples are illustrated. In thefigures, the thicknesses of lines, layers and/or regions may beexaggerated for clarity.

FIG. 1 shows a head-mountable display device for displaying an imagereceived from a microscope according to an embodiment. Thehead-mountable display device 100 comprises a first display 10configured to display a first image of a part of an object 14, the firstimage received from a microscope 12. Further, the head-mountable displaydevice 100 comprises a first optical arrangement 30 located in front ofthe first display 10. The first optical arrangement 30 comprises atleast one lens 32. Additionally, the head-mountable display device 100comprises a mounting structure 20 configured to fasten the first display10 to the head of a user. The head-mountable display device 100 isconfigured to allow a direct line of sight 16 from a first eye of theuser to the object 14 in a field of view of the user outside of thefirst display 10 while the user is watching the first display 10 throughthe first optical arrangement, if the mounting structure 20 is fastenedto the head of a user. A viewing angle between a display direction 18and the direct line of sight is less than 50° (or less than 45° or lessthan 40°) and the display direction 18 is orthogonal to the firstdisplay 10.

The head-mountable display device 100 may allow the direct line of sight16 to the object 14 due to the size and/or geometry of the first display10, the first optical arrangement 30 and/or the position and/or thedistance of the first optical arrangement 30 to the eye of the user, forexample. By using a first display 10 and/or a first optical arrangement30 as described below, the size of the display and optical arrangementmay be kept low and/or the distance to the eye can be kept large so thata direct line of sight at a viewing angle of less than 50° may beenabled, for example. In this way, the user may have an unblocked viewto object at the periphery outside the first display 10 while the userwatches the first image on the display. For example, a brain surgeon mayhave a direct line of sight outside the display to the body or the headof a patient and/or to tools in his hands or close to the head of thepatient while watching a magnification of the site of surgery on thedisplay. In this way, the surgeon may have a far better control and/orunderstanding of on his environment in comparison to a blockedperipheral view.

For example, the direct line of sight 16 may be a straight line betweenthe eye of the user (e.g. the pupil of the eye of the user) and theobject 14 without any opaque or intransparent structure in between orwithout any structure at all in between. The field of view of the usermay be unblocked outside the first display 10 and/or the first opticalarrangement 30. If the user watches an image on the first display 10through the first optical arrangement 30, the user may be still able tosee his environment at view angles larger than 50° (or larger than 45°or larger than 40°). For example, the viewing angle is measured betweenthe display direction 18 and the direct line of sight 16. The displaydirection 18 may be orthogonal to a front side of the first display 10.For example, the display direction 18 may be orthogonal to the frontside of the first display 10 at a center of the first display 10. Thehead-mountable display device 100 may be configured to allow the directline of sight 16 from a first eye of the user to the object 14 in afield of view of the user outside of the first display 10 while thedisplay direction 18 is aligned to the first eye of the user. Forexample, the head-mountable display device 100 may be configured toallow the direct line of sight 16 over a field of at least 180° (or atleast 160° or at least 140°) around the first display 10. Thehead-mountable display device 100 may be configured to allow the directline of sight 16 at least below the first display 10.

The mounting structure 20 is configured to fasten, secure, affix and/ormount the first display 10 to the head of a user. The mounting structure20 may comprise various structural features to enable a secure andstable mounting of the head-mountable display device 100 on the head ofa user. For example, the mounting structure 20 may comprise a headband,a head strap, an adjustable frame and/or a head suspension arrangementconfigured to distribute a weight of the head-mountable display device10 over the head of the user. The mounting structure 20 may beconfigured to carry a weight (e.g. the complete weight) of the firstdisplay 10. The mounting structure 20 may be configured to rest lessthan 40% (or less than 50%, less than 30% or less than 20%) of theweight of the head-mountable display device or no weight of thehead-mountable display device on the nose of the user (e.g. through anose piece). By reducing the weight on the nose of the user, the wearingcomfort of the head-mountable display device 10 can be significantlyincreased, while a stability and/or alignment to the eye of thehead-mountable display device 10 can still be ensured. For example, themounting structure 20 may comprises an alignment piece (e.g. a nosepiece) which is configured to control an alignment of the head-mountabledisplay device 10 to the user when fastened to the head of the user. Bycontrolling the alignment of the head-mountable display device 10 to theeye of the user, for example by a nose piece, the stability may beimproved and/or the misalignment due to movement may be reduced. Themounting structure 20 may be configured to allow an adjustment of aposition of the first display 10 to an interpupillary distance of theuser. In this way, the alignment of the position of the first display 10and the first optical arrangement 30 to the eye of the user can beimproved.

The first optical arrangement 30 may comprise optical elements (e.g. theat least one lens) in order to magnify the image on the first display 10for the user. The first optical arrangement 30 may be attached (e.g.glued) to the front surface of the first display 10. For example, thedisplay direction of the first display 10 may be parallel to an opticalaxis of the first optical arrangement 30. The at least one lens of thefirst optical arrangement 30 may be an aspheric lens. The aspheric lensmay enable to reduce size and weight in comparison to a spherical lens.For example, the first optical arrangement 30 may comprise at leastthree lenses. Three lenses may enable a good optical performance withrespect to magnification and aberrations. For example, the first opticalarrangement 30 comprises at least three aspheric lenses. The asphericlenses may enable to reduce size and weight in comparison to sphericallenses while three lenses may enable a good optical performance withrespect to magnification and aberrations. Additionally or alternatively,the first optical arrangement 30 may be configured to allow anadjustment of its diopter. In this way, the user may be able to adaptthe device to his individual eye.

For example, the head-mountable display device 100 may be configured toallow a direct line of sight 16 from a first eye of the user to theobject 14 in a field of view of the user outside of the first opticalarrangement 30 while the user is watching the first display 10 throughthe first optical arrangement 30, if the mounting structure 20 isfastened to the head of a user. The viewing angle between the opticalaxis of the first optical arrangement 30 and the direct line of sightmay be less than 50° (or less than 45° or less than 40°). For example,the viewing angle of less than 50° may be measured between the opticalaxis of the first optical arrangement 30 and the direct line of sight16.

The head-mountable display device 100 may further comprise a seconddisplay 40 configured to display a second image of the part of theobject. The second image may be received from the microscope. The firstimage and/or the second image may be part of a live stream of imagesfrom the microscope. The second display 40 may be attached to themounting structure 20 in the same or similar way as the first display10. The second display 40 may be positioned relative to the firstdisplay 10 so that the user can watch the first display 10 with thefirst eye and the second display 40 with the second eye. The mountingstructure 20 may be configured to fasten the second display 40 to thehead of the user. The first image and/or the second image may betransmitted to the head-mountable display device 100 over a wired orwireless connection.

The first display 10 and/or second display 40 may be an LCD display(Liquid Crystal Display), a TFT display (Thin-film transistor-Display)or an OLED display (organic light-emitting diode display). A displaydiagonal of the first display 10 and/or the second display 40 may be atleast 0.5 inch (or at least 0.6 inch) and/or at most 1 inch (or at most0.8 inch).

By using two independent displays, the distance between the displays maybe adjustable. For example, the mounting structure 20 may be configuredto allow an adjustment of a distance of the first display 10 to thesecond display 40. In this way, the user may adjust the distance betweenthe two displays to the individual interpupillary distance of the user.

Alternatively to a second display, a first part of the first display 10is configured to display the first image and a second part of the firstdisplay 10 is configured to display the second image of the part of theobject. For example, the first display 10 is configured to work in asplit screen mode with a first part of the display showing images for afirst eye of the user and the second part of the display showing imagesfor the second eye of the user. By using a single display, the number ofcomponents of the head-mountable display device 100 may be reduced.

Independent from whether two displays or a single display are used, thefirst image and the second image may be configured to allow forstereoscopic vision. The user may obtain a three-dimensional impressionof the object or a part of the object when watching the first image withthe first eye and the second image with the second eye simultaneously.

The object 14 may be a human body, a part of a human body (e.g. the heador chest), a site of surgery or a microelectronic device (e.g. asemiconductor chip). The user may be a surgeon or any other person inneed of a magnified image of an object.

For example, the same object, which is shown on the display, can be seenin the peripheral view. For example, the first image may show a part ofa surface of the object and the surface of the object or another part ofthe surface of the object may be in the field of view of the useroutside the display. For example, the first image may show a part of asurface of a human brain during surgery and the surface of the humanbrain can also be seen by the user in the peripheral view.

The peripherical view might not be limited to the directions outside andbelow of the headmountable display device 100. It may also be possibleto look (e.g. with some limitations) above and to the inner direction(e.g. towards the nose). For example, this may be enabled by arrangingthe display in coaxial direction of the viewing direction of the eye.Even if the peripherical viewing performance might not be ideal in theseadditional directions, it may give the user the opportunity to interactwith its environment.

The head-mountable display device 100 may also be called digital vieweror digital eyepieces. The head-mountable display device 100 may be adevice, which can be carried on the head of a user and has a display forshowing images, videos and/or live streams to the user. Theheadmountable display device 100 may comprise various additionaloptional components as, for example, an energy storage device (e.g. oneor more power banks) and/or a receiver (e.g. one or more wireless imagereceivers). For example, the energy storage device may provide a powersupply for the first display 10 and/or may be attached to the mountingstructure 20 of the head-mountable display device 100 or may beattachable to a part of the user except the head (e.g. through a waistband or an arm band). The receiver may be a wired or wireless receiver.For example, the head-mountable display 100 may be configured to receivethe image wirelessly. The receiver may be configured to receive theimage to be displayed by the first display 10. The head-mountabledisplay device 100 may be configured so that a weight of at most 600 g(or at most 700 g, at most 500 g or at most 400 g) rest on the head ofthe user, while using the head-mountable display device 100. The overallweight of the head-mountable display device 100 may be larger, but theremaining weight (e.g. for the energy storage device and/or thereceiver) may be carried by other parts of the body of the user (e.g.through a waist band or an arm band).

For example, a latency of the head-mountable display device may be atmost 70 ms (or at most 90 ms, at most 60 ms or at most 50 ms). Thelatency may be the time between receiving an image at the receiver ofthe head-mountable display device 100 and displaying the image on thefirst and/or second display. By using fast electrical components for thereceiver and/or the display and/or additional image processingcomponents, the head-mountable display device 100 may be able to displaylive or real-time images or video streams of at least a part of theobject 14.

The head-mountable display device 100 may be usable with different kindof microscopes. The head-mountable display device 100 may be connectableto any microscope with a suitable interface. For example, the microscope12 may be a digital stereo microscope or a digital microscope with onlyone camera to visualize on object in 2D (e.g. the image from the solecamera may be duplicated and this unique image may be inject in bothdisplays or in only on channel, if only one display is implemented). Themicroscope is not part of the head-mountable display device 100.

More details and aspects of the head-mountable display device 100 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIGS. 2-11 ). The head-mountabledisplay device 100 may comprise one or more additional optional featurescorresponding to one or more aspects of the proposed concept and/or ofone or more examples described above or below.

FIG. 2 shows a schematic illustration of a head-mountable display device200 comprising two displays according to an embodiment. Thehead-mountable display device 200 may be implemented similar to theimplementation described in connection with FIG. 1 . The first display10 and the second display 40 may be attached to the mounting structure20. The second display 40 may be positioned relative to the firstdisplay 10 so that the user can watch the first display 10 with thefirst eye and the second display 40 with the second eye. A first opticalarrangement 30 is mounted to the front side of the first display 10 anda second optical arrangement 50 is mounted to the front side of thesecond display 40. The first optical arrangement 30 and the secondoptical arrangement 50 may comprise one or more optical elements (e.g.lenses). The second optical arrangement 50 may be implemented similar orequal to the first optical arrangement 30 with respect to the number andtype of lenses.

More details and aspects of the head-mountable display device 200 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIG. 1 or 3-11 ). Thehead-mountable display device 200 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIG. 3 shows a head-mountable display device 300 allowing an adjustmentof the interpupillary distance according to an embodiment. Thehead-mountable display device 300 may be implemented similar to theimplementation described in connection with FIG. 2 . In addition, themounting structure 20 is configured to allow an adjustment of a distanceof the first display 10 to the second display 40. In this way, the usermay adjust the distance between the two displays to the individualinterpupillary distance. Further, the first optical arrangement 30 maybe configured to allow an adjustment of its diopter. For example, adistance between one or more optical elements (e.g. lenses) to thedisplay may be adjustable. In this way, the user may be able to adaptthe device to his individual eye.

More details and aspects of the head-mountable display device 300 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIG. 1-2 or 4 a-11). Thehead-mountable display device 300 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIGS. 4 a and 4 b shows a head-mountable display device 400 according toan embodiment. The head-mountable display device 400 may be implementedsimilar to the implementation described in connection with FIG. 1, 2 or3 . In addition the head-mountable display device 400 is configured toallow at least partial removal of the first display 10 from the field ofview of the user. For example, the first display 10 may be manually orautomatically rotatable or slidable at least partly out of the view ofthe user. For example, the mounting structure 20 may be configured toremove the first display 10 automatically in response to an identifiedevent (e.g. receive a control signal caused by the user or by automaticdetection of an event). FIG. 4 a shows the head-mountable display device400 in a first state (e.g. normal use stage). In the first state, thedisplay direction of the first display 10 and/or the optical axis of thefirst optical arrangement 30 may be aligned to the eye of the user. Forexample, the optical axis of the first optical arrangement 30 passesthrough the pupil of the eye of the user in the first state. FIG. 4 bshows the head-mountable display device 400 in a second state (e.g.removed state). In the second state, the user may have a direct and/orunblocked line of sight to the object in the center of the field of viewof the user. In the second state, the first display 10 and the firstoptical arrangement 30 are located at a position so that the displaydirection of the first display 10 and/or the optical axis of the firstoptical arrangement 30 is not aligned to the eye of the user. In thesecond state, the optical axis of the first optical arrangement 30 doesnot extend to the eye of the user, for example. The mounting structure20 may comprise a hinge 28 configured to at least partially remove thefirst display 10 from the field of view of the user as shown in FIGS. 4a and 4 b . The first display 10 may be mechanically connected to thehinge 28. Alternatively or additionally, the mounting structure 20 maycomprise a sliding mechanism configured to at least partially remove thefirst display 10 from the field of view of the user. The first display10 may be mechanically connected to the sliding mechanism.

FIGS. 4 a and 4 b may show an example of a viewer (head-mountabledisplay device), which may contain a mechanism for moving the optics outof the users view. This movement may be realized automated and/ormanually and may enable a change from digital view to direct view.

More details and aspects of the head-mountable display device 400 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIG. 1-3 or 5 a-11). Thehead-mountable display device 400 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIGS. 5 a and 5 b show a head-mountable display device 500 according toan embodiment. The head-mountable display device 500 may be implementedsimilar to the implementation described in connection with FIG. 1 . Thehead-mountable display device 500 enables a direct line of sight from afirst eye of the user to the object in a field of view of the useroutside of the first display 10 and the first optical arrangement 30while the user is watching the first display 10 through the firstoptical arrangement 30 while the mounting structure 20 is fastened tothe head of a user. The viewing angle 17 between the display direction18 and the direct line of sight 16 is at least 43°. Further, thehead-mountable display device 500 is configured to allow the direct lineof sight 16 over a field of at least 180° around the first display 10.

More details and aspects of the head-mountable display device 500 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIGS. 1-4 b or 5 c-11). Thehead-mountable display device 500 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIG. 5 c shows a side view of a head-mountable display device 550according to an embodiment. The head-mountable display device 550 may beimplemented similar to the implementation described in connection withFIG. 1 . The head-mountable display device 550 is configured to betilted relative to a reference plane 552 of the head-mountable displaydevice 550. In FIG. 5 c , the display direction 18 of the display and/orthe optical axis of the optical arrangement is in parallel with thereference plane 552. In FIG. 5 d , the display direction 18 of thedisplay and/or the optical axis of the optical arrangement is tilted by−5° below the reference plane 552. In FIG. 5 e the display direction 18of the display and/or the optical axis of the optical arrangement istilted by +5° above the reference plane 552. For example, theheadmountable display device 550 may be configured to be tilted relativeto a reference plane 552 of the head-mountable display device 550 atleast by +/−10° and/or at most by +/−20°. The head-mountable displaydevice 550 may comprise a tilt adjuster 554 for manual adjustment of thetilt arranged on a side of the display opposite to the side of theoptical arrangement and between the eyes of the user.

More details and aspects of the head-mountable display device 550 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIGS. 1-5 b or 5 f-11). Thehead-mountable display device 550 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIG. 5 f shows a side view of a head-mountable display device 590according to an embodiment. The head-mountable display device 590 may beimplemented similar to the implementation described in connection withFIG. 1 . The head-mountable display device 590 is configured to allow anadjustment of the distance between the optical arrangement and the eyeof the user. In FIG. 5 f , a distance offset with respect to a referencedistance 592 between the optical arrangement and the eye of the user iszero. In FIG. 5 g , a distance offset 596 with respect to the referencedistance 592 between the optical arrangement and the eye of the user is+6 mm. In FIG. 5 h , a distance offset 596 with respect to the referencedistance 592 between the optical arrangement and the eye of the user is−6 mm. For example, the head-mountable display device 590 may beconfigured to allow an adjustment of the offset distance 596 at least by+/−10 mm and/or at most +/−15 mm with respect to the reference distance592. The head-mountable display device 590 may comprise a distanceadjuster 594 for manual adjustment of the distance. The distanceadjuster 594 may be arranged on a side of the display opposite to theside of the optical arrangement and between the eyes of the user.

The head-mountable display device 590 may comprise additionally a tiltadjuster 554 for manual adjustment of the tilt as described inconnection with FIGS. 5 c-5 e . For example, the tilt adjuster 554 andthe distance adjuster 594 may be rotatable around a mutual axis, but mayenable an adjustment of tilt and distance independently. The distanceadjuster 594 may be arranged between the tilt adjuster 554 and thedisplay.

More details and aspects of the head-mountable display device 590 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIGS. 1-5 e or 6-11). Thehead-mountable display device 590 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIG. 6 is an example of a possible user view for one of thehead-mountable display devices described above or below. FIG. 6 shows anexample of a left channel image 610 on the first display 10, a rightchannel image 620 on the second display 40 and the unblocked peripheralview 630 of a site of surgery of a human brain.

FIG. 7 shows a head-mountable display device 700 according to anembodiment and a microscope system 790. The head-mountable displaydevice 700 may be implemented similar to the implementation described inconnection with FIG. 1, 2, 3, 4 a, 4 b, 5 a and/or 5 b. Theheadmountable display device 700 comprises a power bank 710 and awireless image receiver 720 for the first display 10 and a power bank710 and a wireless image receiver 720 for the second display 40.Alternatively, the first display 10 and the second display 40 may besupplied with power by a common power bank 710 and/or may be provided byimages received by a common wireless image receiver 720. The microscopesystem 790 may comprise a digital microscope 792 comprising one or morecameras controlled by one or more camera controllers 794 comprising oneor more wireless image transmitters 796.

More details and aspects of the head-mountable display device 700 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIG. 1-6 or 8-11 ). Thehead-mountable display device 700 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIG. 8 shows a head-mountable display device for displaying an imagereceived from a microscope according to an embodiment. Thehead-mountable display device 800 comprises a first display 10configured to display a first image of a part of an object, the firstimage received from a microscope. Further, the head-mountable displaydevice 800 comprises a mounting structure 20 configured to fasten thefirst display 10 to the head of a user. The mounting structure 20comprises a nose piece 25 configured to align the first display 10 tothe first eye of the user. Further, the mounting structure 20 isconfigured to rest less than 40% (or less than 50%, less than 30% orless than 20%) of the weight of the head-mountable display devicethrough the nose piece 25 on the nose of the user.

The nose piece 25 may be configured (e.g. may comprise a geometry) tocontact the nose of a user at least at one point on a left side of thenose and at least at one point on the right side of the nose, if themounting structure 20 is fastened to the head of a user. In this way, amovement of the head-mountable display device 800 to the right or leftrelative to the nose may be significantly reduced or avoided, if theuser moves his head.

For example, the head-mountable display device 800 is configured so thata weight of at most 250 g (or at most 200 g, at most 150 g or at most100 g) rest on the nose of the user, while using the head-mountabledisplay device 800.

For example, at least 10% (or at least 20% or at least 30%) of theweight of the head-mountable display device may rest on the nose of theuser through the nose piece 25, while the user is using thehead-mountable display device. In this way, a stable alignment may beensured.

More details and aspects of the head-mountable display device 800 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIG. 1-7 or 9-11 ). Thehead-mountable display device 800 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIG. 9 shows a head-mountable display device for displaying an imagereceived from a microscope. The head-mountable display device 900comprises a first display 10 configured to display a first image of apart of an object, the first image received from a microscope. Further,the head-mountable display device 900 comprises a mounting structure 20configured to fasten the first display to the head of a user.Additionally, the head-mountable display device 900 comprises a firstoptical arrangement 30 located in front of the first display 10. Thefirst optical arrangement 30 comprises three lenses 32, 34, 36. Further,at least one lens of the three lenses 32, 34, 36 is an aspheric lens.

By using at least three lenses between the display and the eye of theuser, a good optical performance with respect to magnification andaberrations may be obtainable. By using at least one aspheric lens, thesize and weight of the optical arrangement may be significantly reducedin comparison to a system using only spherical lenses.

For example, the first optical arrangement 30 comprises a first lens 32,a second lens 34 and a third lens 36. The first lens 32 may be the lensof the three lenses closest to the first display 10. The second lens 34may be arranged between the first lens 32 and the third lens 36. Thefirst optical arrangement 30 may comprise exactly three lenses or maycomprise more than three lenses. The three lenses may be glass lenses ormay be made of other suitable material.

The aspheric lens of the three lenses may be the first, second or thirdlens. For example, the aspheric lens may be the second lens 34 while thefirst lens 32 and the third lens may be spherical lenses. Alternatively,all three lenses may be aspheric lenses. In this way, size and weight ofthe first optical arrangement 30 may be kept low.

For example, each lens of the three lenses may comprise a first surfaceand a second surface. The surfaces of the three lenses may represent orform a sequence of surfaces. For example, the first surface of the firstaspheric lens may be a first spherical surface, the second surface ofthe first aspheric lens may be a first aspherical surface, the firstsurface of the second aspheric lens may be a second spherical surface,the second surface of the second aspheric lens may be a secondaspherical surface, the first surface of the third aspheric lens may bea third spherical surface and the second surface of the third asphericlens may be a third aspherical surface. The sequence of surfaces maycomprise a first spherical surface followed by a first asphericalsurface followed by a second spherical surface followed by a secondaspherical surface followed by a third spherical surface followed by athird aspherical surface. For example, the sequence of surfaces does notcontain a diffractive surface. An optical path through the opticalarrangement 30 might not contain a diffractive surface at all.

For example, each lens of the three lenses comprises a different glassmaterial. Three different glass materials may be used for the threelenses. For example, the first lens may comprise or consist of a firstglass material, the second lens may comprise or consist of a secondglass material and the third lens may comprise or consist of a thirdglass material. For example, the first glass material, the second glassmaterial and the third glass material are three different glassmaterials.

For example, the first lens 32 may be a positive lens and/or an asphericlens. A focal length of the first lens 32 may be at most 25 mm (or atmost 20 mm or at most 30 mm) and/or at least 15 mm (or at least 10 mm orat least 20 mm).

For example, the second lens 34 may be a negative lens and/or anaspheric lens. A focal length of the second lens 34 may be at most −15mm (or at most −20 mm or at most −13 mm) and/or at least −5 mm (or atleast −10 mm or at least −3 mm).

For example, the third lens 36 may be a positive lens and/or an asphericlens. A focal length of the third lens 36 may be at most 20 mm (or atmost 25 mm or at most 17 mm) and/or at least 10 mm (or at least 13 mm orat least 7 mm).

By using one or more of the above parameters, a desired viewing angle,overall size, weight and/or exit pupil size may be obtained.

For example, one or more of the three aspheric lenses may be free formlenses. In this way, the size and weight may be further reduced, but thecosts may be increased.

A total weight of the three lenses (e.g. first lens 32, second lens 34and third lens 36) may be at most 30g (or at most 25g, at most 20g or atmost 35g). A diameter of each lens of the three lenses (e.g. first lens32, second lens 34 and third lens 36) may be at most 25 mm (or at most20 mm or at most 30 mm). A total focal length of the first opticalarrangement 30 may be at most 30 mm (or at most 35 mm or at most 25 mm)and/or at least 15 mm (or at least 10 mm or at least 20 mm). A totaloptimal distance between the first display 10 and an eye of a usercaused by the first optical arrangement 30 may be at most 60 mm (or atmost 70 mm, at most 55 mm or at most 50 mm). By implementing the firstoptical arrangement 30 with one or more of the mentioned parameters,size and/or weight of the first optical arrangement 30 and thehead-mountable display device 900 may be kept low.

A display diagonal of the first display 10 may be at least 0.5 inch (orat least 0.6 inch) and/or at most 1 inch (or at most 0.8 inch). In thisway, a sufficiently large image can be displayed while the weight may bekept low.

The head-mountable display device 900 may comprise a second display anda second optical arrangement as described in connection with some otherexamples.

More details and aspects of the head-mountable display device 900 arementioned in connection with the proposed concept and/or the one or moreexamples described above or below (e.g. FIG. 1-8 or 10-11 ). Thehead-mountable display device 900 may comprise one or more additionaloptional features corresponding to one or more aspects of the proposedconcept and/or of one or more examples described above or below.

FIG. 10 shows an optical arrangement 1000 for a head-mountable displaydevice according to an embodiment. The optical arrangement 1000 may beimplemented similar to the implementation of the first opticalarrangement described in connection with FIG. 1 and/or 9 . The opticalarrangement 1000 comprises three aspheric lenses. The first lens 32 is apositive lens, the second lens 34 is a negative lens and the third lens36 is a positive lens. A total focal length of the optical arrangement1000 is at most 30 mm and at least 15 mm. A focal length of the firstlens 32 is at most 25 mm and at least 15 mm, a focal length of thesecond lens 34 is at most −15 mm and at least −5 mm and a focal lengthof the third lens 36 is at most 20 mm and at least 10 mm. A total weightof the three lenses 32, 34, 36 is at most 30 g. A diameter of each lensof the three lenses 32, 34, 36 is at most 25 mm. A total optimaldistance between the first display 10 and an eye of a user caused by theoptical arrangement 1000 is at most 60 mm.

The optical arrangement 1000 shown in FIG. 10 may be used as firstoptical arrangement and/or second optical arrangement of one of thehead-mountable display devices described above or below.

More details and aspects of the optical arrangement 1000 are mentionedin connection with the proposed concept and/or the one or more examplesdescribed above or below (e.g. FIG. 1-9 or 11 ). The optical arrangement1000 may comprise one or more additional optional features correspondingto one or more aspects of the proposed concept and/or of one or moreexamples described above or below.

FIG. 11 shows a flowchart of a method for displaying an image receivedfrom a microscope according to an embodiment. The method 1100 comprisesreceiving 1110 a first image of a part of an object from a microscopeand displaying 1120 the first image on a first display of ahead-mountable display device fastened to a head of the user by amounting structure of the head-mountable display device. Thehead-mountable display device is configured to allow a direct line ofsight from a first eye of the user to the object in a field of view ofthe user outside of the first display while the user is watching thefirst display through a first optical arrangement, if the head-mountabledisplay device is fastened to the head of a user by a mountingstructure. Further, an angle between a display direction and the directline of sight is less than 50°. Additionally, the display direction isorthogonal to the first display and the first optical arrangementlocated in front of the first display and comprises at least one lens.

More details and aspects of the method 1100 are mentioned in connectionwith the proposed concept and/or the one or more examples describedabove or below (e.g. FIGS. 1-10 ). The method 1100 may comprise one ormore additional optional features corresponding to one or more aspectsof the proposed concept and/or of one or more examples described aboveor below.

Some embodiments relate to a head-mounted device to digitally visualize,in live, images from a digital microscope and/or a head-mounted digitalviewer or digital eyepieces according to one of the examples describedabove. In comparison to systems, which completely enclose the user andblock the peripheral view of the user by the goggles, the proposedsystem enables an unblocked peripheral view, for example. Further, incomparison to systems with heavy digital viewers, the proposed systemmay provide an improved stability so that the alignment of each eye infront of each channel can be kept. The digital viewer may comprise twoseparate channels, one per eye. Each channel may comprise one or severaloptical element(s) and a display (e.g. see FIG. 2 ).

The optics may be used to magnify the view of the display and may allowstereo view of the images transmitted by the digital microscope. Theoptics may be designed to be light weight (e.g. to avoid head/musclepain since the device is worn on the head), may be compact and may allowunblocked peripheral view for the user (e.g. to allow the surgeon, forexample, to see tools, hands and assistants if necessary) as shown inFIG. 6 , for example.

The mechanics may be designed to be light weight, compact and ergonomicto allow unblocked peripheral view. The cables for image transmissionand power supply may be handled by the mechanics. The digital viewer maybe powered and may receive the images in a wireless way. For example,the digital viewer may use power banks and image transmission dongles.

The digital viewer may be mounted on the head or the body of the userand may be positioned by a resting part which sits on the nose to alignthe two optical channels to the eyes, for example. The digital viewergeometry may be based on the middle part of most glasses and providestogether with the head strap the necessary stability of the displaymodule to the individual eye. This resting concept (e.g. orientationcontrolled on the nose and fixation with straps on the head) mayovercome the disadvantages of pure goggle or pure head mountedsolutions.

The whole viewer may be held in place by a strap or an adjustable framearound the head. The mechanics may be designed to fit individual headgeometries by one or several adjustment options and may contain amechanism for moving the optics out of the users view.

A proposed head-mountable display device may enable an adaptation of thetwo digital channels individually for diopter mismatch andinterpupillary distance, a live simultaneous microscopic view andperipherical view, a change from digital view to direct view, apositioning of the digital viewer with the combination of rest pads onnose and stripe on head, and/or a wireless connection and mobile powersupport.

For example, to get a stereoscopic impression with a visual microscopeboth visual channels have to be adjusted in that way, that the exitpupil of the individual eyepiece meets the pupil of the human eye. Thismay be realized with the opportunity of interpapillary distance (IPD)adjustment. In comparison to a pure visual microscope, the opticalsystem of the digital viewer may provide an image outside its designedexit pupil. The best location for the human eye may be the central axisof the individual eye piece. If both eyes are not located at the ideallateral position—even if the IPD is adjusted correctly—the opticalperformance of the system may suffer. This can result in differentaberrations in the image up to the missing ability to generate thestereoscopic impression. The design of the proposed optical system mayprevent this risk with the respective effort (e.g. number and shape oflenses).

The optical design with 3 aspherical lenses may be chosen to optimizesize and weight of the optical module. For example, element(s) may beused that bring the display content to infinite to have relaxed view ofit at a desired magnification and in a compact way with diopteradjustment and the possibility to use glasses. For example, 3 lensescausing a total length (display to eye) of less than 60 mm may be used.

As used herein the term “and/or” includes any and all combinations ofone or more of the associated listed items and may be abbreviated as“/”.

Although some aspects have been described in the context of anapparatus, it is clear that these aspects also represent a descriptionof the corresponding method, where a block or device corresponds to amethod step or a feature of a method step. Analogously, aspectsdescribed in the context of a method step also represent a descriptionof a corresponding block or item or feature of a correspondingapparatus.

LIST OF REFERENCE SIGNS

-   10 first display-   12 microscope-   14 object-   16 direct line of sight-   17 viewing angle-   18 display direction-   20 mounting structure-   25 nose piece-   28 hinge-   30 first optical arrangement-   32 first lens-   34 second lens-   36 third lens-   40 second display-   50 second optical arrangement-   100 head-mountable display device-   200 head-mountable display device-   300 head-mountable display device-   310 interpupillary distance adjustment-   320 diopter adjustment-   400 head-mountable display device-   500 head-mountable display device-   550 head-mountable display device-   552 reference plane-   554 tilt adjuster-   590 head-mountable display device-   592 reference distance-   594 distance adjuster-   596 distance offset-   610 left channel-   620 right channel-   630 unblocked peripheral view-   700 head-mountable display device-   702 supply unit-   710 energy storage device-   720 wireless image receiver-   790 microscope system-   792 digital microscope-   794 camera controller-   796 wireless image transmitter-   800 head-mountable display device-   900 head-mountable display device-   1000 optical arrangement-   1100 method for displaying an image received from a microscope-   1110 receiving a first image-   1120 displaying the first image

1. Head-mountable display device for displaying an image received from amicroscope, comprising: a first display configured to display a firstimage of a part of an object, the first image received from amicroscope; a first optical arrangement located in front of the firstdisplay, wherein the first optical arrangement comprises at least onelens; and a mounting structure configured to fasten the first display tothe head of a user, wherein the head-mountable display device isconfigured to allow a direct line of sight from a first eye of the userto the object in a field of view of the user outside of the firstdisplay while the user is watching the first display through the firstoptical arrangement, if the mounting structure fastened to the head of auser, wherein an angle between a display direction and the direct lineof sight is less than 50°, wherein the display direction is orthogonalto the first display, wherein the head-mountable display device isconfigured to allow the direct line of sight over a field of at least180° around the first display.
 2. Head-mountable display deviceaccording to claim 1, wherein the first optical arrangement comprises atleast three lenses.
 3. Head-mountable display device according to claim2, wherein the first optical arrangement comprises at least threeaspheric lenses.
 4. Head-mountable display device according to claim 1,wherein the first optical arrangement is configured to allow anadjustment of its diopter.
 5. Head-mountable display device accordingclaim 1, wherein the head-mountable display is configured to receive theimage wirelessly.
 6. Head-mountable display device according claim 1,further comprising a second display configured to display a second imageof the part of the object, the second image received from themicroscope, wherein the mounting structure is further configured tofasten the second display to the head of the user.
 7. Head-mountabledisplay device according to claim 6, wherein the mounting structure isfurther configured to allow an adjustment of a distance of the firstdisplay to the second display.
 8. Head-mountable display deviceaccording to claim 1, wherein a first part of the first display isconfigured to display the first image and a second part of the firstdisplay is configured to display a second image of the part of theobject, the second image received from the microscope.
 9. Head-mountabledisplay device according to claim 6, wherein the first image and thesecond image are configured to allow for stereoscopic vision. 10.Head-mountable display device according claim 1, wherein the mountingstructure comprises an alignment piece which is configured to control analignment of the head-mountable display device to the user when fastenedto the head of the user.
 11. Head-mountable display device according toclaim 10, wherein the alignment piece is a nose piece configured toalign the first display to the first eye of the user.
 12. Head-mountabledisplay device according claim 1, wherein the mounting structure isconfigured to rest less than 40% of the weight of the head-mountabledisplay device on the nose of the user.
 13. Head-mountable displaydevice according claim 1, wherein the mounting structure is configuredto carry a weight of the first display.
 14. Head-mountable displaydevice according claim 1, wherein the mounting structure comprises aheadband.
 15. Head-mountable display device according claim 1, furthercomprising an energy storage device configured to provide a power supplyfor the first display.
 16. Head-mountable display device according toclaim 15, wherein the energy storage device is attachable to a part ofthe user except the head.
 17. Head-mountable display device accordingclaim 1, wherein the mounting structure is further configured to allowat least partial removal of the first display from the field of view ofthe user.
 18. Head-mountable display device according to claim 17,wherein the mounting structure is configured to remove the first displayautomatically in response to an identified event.
 19. Head-mountabledisplay device according to claim 17, wherein the mounting structurefurther comprises a hinge configured to at least partially remove thefirst display from the field of view of the user, wherein the firstdisplay is mechanically connected to the hinge.
 20. Head-mountabledisplay device according claim 1, wherein the mounting structure isconfigured to allow an adjustment of a position of the first display toan interpupillary distance of the user.
 21. Head-mountable displaydevice according claim 1, wherein the head-mountable display device isconfigured to allow a direct line of sight from a first eye of the userto the object in a field of view of the user outside of the firstdisplay while the display direction is aligned to the first eye. 22.Head-mountable display device for displaying an image received from amicroscope, comprising: a first display configured to display a firstimage of a part of an object, the first image received from amicroscope; a mounting structure configured to fasten the first displayto the head of a user; and a first optical arrangement located in frontof the first display, wherein the first optical arrangement comprisesthree lenses comprising a first aspheric lens, a second aspheric lensand a third aspheric lens, wherein the first aspheric lens is the lensof the three lenses closest to the first display, wherein the secondaspheric lens is arranged between the first aspheric lens and the thirdaspheric lens, wherein each lens of the three lenses comprises a firstsurface and a second surface, wherein the surfaces of the three lensesrepresent a sequence of surfaces, wherein the sequence of surfacescomprises a first spherical surface followed by a first asphericalsurface followed by a second spherical surface followed by a secondaspherical surface followed by a third spherical surface followed by athird aspherical surface. 23-35. (canceled)
 36. Method for displaying animage received from a microscope, comprising: receiving a first image ofa part of an object from a microscope, displaying the first image on afirst display of a head-mountable display device fastened to a head ofthe user by a mounting structure of the head-mountable display device,wherein the head-mountable display device is configured to allow adirect line of sight from a first eye of the user to the object in afield of view of the user outside of the first display while the user iswatching the first display through a first optical arrangement, if thehead-mountable display device is fastened to the head of a user by amounting structure, wherein an angle between a display direction and thedirect line of sight is less than 50°, wherein the display direction isorthogonal to the first display, wherein the first optical arrangementlocated in front of the first display and comprises at least one lens,wherein the head-mountable display device is configured to allow thedirect line of sight over a field of at least 180° around the firstdisplay.